1. Field of the Invention
The present invention relates to a structure for connection between a flat electrical cable and individual electrical cables. More particularly, the invention concerns a water-proof connecting structure. Such a connecting structure can be used in automobile parts which receive water, and ensures the water impermeability of the joint section between the flat cable and the electrical cables.
2. Description of Background Information
Automobile doors or other parts contain wire harnesses wired thereto, while electrical cables are wired in the automobile body. The electrical cables are then led out from the car body, and connected to a flat electrical cable (sometimes referred to as xe2x80x9cribbon cablexe2x80x9d) wired inside the door. However, as the window glass of the door is moved up and down, inside the door, there is a possibility of water seepage into a joint section between electrical cables and a flat cable. Although there has existed a strongly felt need to improve the imperviousness of this section, the solution was found difficult to implement from a practical point of view.
FIG. 1 shows a joint section between a flat cable and corresponding electrical cables. As the figure shows, the flat cable 1 includes an end portion in which conductor elements la are exposed. Likewise, each of the electrical cables 2 includes an end portion where a core wire group 2a is exposed. The corresponding conductor elements la and core wire groups 2a are then superposed and bonded by resistance welding, ultrasonic welding, or the like. A Japanese patent application published under the publication No. HEI 9-167648 discloses a structure connecting a flat cable conductor to bus bars, as shown in FIG. 2. In this structure, the bus bars 3 and the electrical conductor 1a of flat cable 1 are connected, and the joint section is held by a holder 4. A hot-melt-type bonding layer is then formed on the flat cable 1 and heated, so that the conductor 1a and the bus bars 3 are connected by melting.
Alternatively, the bus bars 3 shown in FIG. 2 may be replaced by electrical cables 2. The conductor portion of flat cable 1 and the core wire portion of electrical cables 2 are then put together to form a joint section. Subsequently, the joint section is held by a holder, and linked with a bond. However, in this case too, the joint section is not sufficiently protected from water, and cannot be used in locations where there is frequent water seepage.
In view of the above, the main object of the present invention is to provide a water-proof structure for connecting a flat cable to electrical cables.
To this end, there is provided a structure for connecting electrical cables to a flat electrical cable, the respective electrical cables and the flat electrical cable including a coated portion, and an end portion where a conductor element is exposed from the coatings. Further, part of each of the coated portions adjacent the end portions is surrounded with a sealing material. The end portion of the respective electrical cables and that of the flat electrical cable are then superposed, thereby forming a joint section. Subsequently, the joint section and the part of each of the coated portions adjacent the end portions are molded with an insulator resin, whereby the sealing material is adhered to the coated portion of the respective electrical cables and the flat electrical cable.
The end portion of the respective electrical cables may include a group of core wires and the end portion of the flat electrical cable may include a corresponding conductor element.
Preferably, the sealing material used is an elastic material.
Suitably, the sealing material includes a butyl rubber tape wound around the respective electrical cables and the flat electrical cable.
Alternatively, the sealing material may include at least one of nitrile rubber and epichlorohydrin, and may be painted around the electrical cables and the flat electrical cable.
Further, the structure may contain a shell with grooves, the shell including the joint section held in the grooves, and being molded with an insulator resin.
In the above structure, the elastic sealing materials are adhered to the outer surface of the electrical cables and the flat electrical cable by compression under the insulator resin.
The flat electrical cable is formed by arranging conductor strips made of copper foil at a given parallel interval, and coating both faces of the strips with an insulator resin. The end portion of the flat cable is stripped of the coating, so that the conductor elements are exposed. Likewise, there is provided a number of electrical cables corresponding to that of the exposed conductor elements. The end portion of these electrical cables is stripped of the coating, so that the core wire groups are exposed. The conductor elements and the core wire groups are superposed, and bonded by ultrasonic welding, resistance welding or a similar means. The flat electrical cable and the electrical cables are then inserted into a die, and insert-molded by filling the die with the insulator resin. When the insert-molding is performed, the elastic sealing materials surrounding the electrical cables and the flat electrical cable are crushed by compression, and firmly adhered around the outer circular surface of the corresponding cables.
As the joint section between the conductor elements of the flat cable and the core wire groups of electrical cables is insert-molded, water penetration can be avoided. Likewise, even if water penetrates through the apertures formed by the cables leading out from the molded structure, it is stopped by the adhered sealing materials, so that the water cannot reach the joint section.
The joint section between the core wire groups of the electrical cables and the conductor elements of the flat electrical cable is fixedly positioned in the grooves provided in a shell, and the shell is molded with an insulator resin.
When such a shell is used, the protection of the joint section is further enforced by the rigid body of the shell, so that the electrical connections are made even more reliable.